1. Field of the Invention
The present invention relates to a vent or breather assembly, and more particularly, to an explosion proof breather assembly for electrical enclosures that is simply constructed and reliable.
2. Description of the Related Art
Water and moisture are the leading causes of corrosion and gradual deterioration of electrical components within an electrical enclosure. Enclosed electrical systems are frequently found in hostile environments. Examples of such hostile environments include ocean-going ships, cold climates and chemical factories. The primary function of a breather assembly is to provide adequate ventilation for the electrical system. Frequently a drain is also used with the enclosed system for allowing water that accumulates in the electrical system to be removed, while a breather assembly serves as a means to allow air to enter and exit the electrical enclosure. A major requirement for such a breather assembly is that it must preclude water from outside the breather assembly, such as rain or cleaning water, from entering the electrical system.
While the breather assembly serves as a means for air to move into and out of an enclosed electrical system, the assembly itself must also be explosion proof. If not, an explosion generated in one part of an electrical system may propagate through interconnected components of the system to another location and thus greatly enhance the spread of a fire.
There is a standard specification, referred to as NEMA 4X, that determines how well a breather assembly resists the entry of water into an electrical enclosure as well as its level of resistance to corrosion when exposed to a salt spray for 200 hours. To determine whether a design is water tight, it is subjected to a steady stream of water for five minutes from a hose positions from ten to twelve feet away. The hose has a one inch nozzle and delivers water at a 65 gallons per minute rate. Present breather assemblies which claim to have a NEMA 4X rating frequently fail the relevant specification. The need, therefore, for a true NEMA 4X rated breather assembly is very important.